Exact Results for the Asymptotic Dispersion of Particles inn-Layer Systems

A fluid flows parallel to the strata of an $n$-layer stratified system. Particles suspended in the fluid are carried along with the flow, and additionally make random jumps into neighboring strata, where the flow velocity is different. The spatial dispersion of the particles in the flow direction, for long times, is calculated exactly for arbitrary $n$, jump rates, and velocity field. The result is applied to a variety of phenomena, e.g., chromatography, Taylor diffusion, and random walks.